__fput doesn't need a cdev_put() for O_PATH handles.

Signed-off-by: mszeredi@suse.cz
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Just need to make sure that AF_UNIX garbage collector won't
confuse O_PATHed socket on filesystem for real AF_UNIX opened
socket.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

New flag for open(2) - O_PATH.  Semantics:
	* pathname is resolved, but the file itself is _NOT_ opened
as far as filesystem is concerned.
	* almost all operations on the resulting descriptors shall
fail with -EBADF.  Exceptions are:
	1) operations on descriptors themselves (i.e.
		close(), dup(), dup2(), dup3(), fcntl(fd, F_DUPFD),
		fcntl(fd, F_DUPFD_CLOEXEC, ...), fcntl(fd, F_GETFD),
		fcntl(fd, F_SETFD, ...))
	2) fcntl(fd, F_GETFL), for a common non-destructive way to
		check if descriptor is open
	3) "dfd" arguments of ...at(2) syscalls, i.e. the starting
		points of pathname resolution
	* closing such descriptor does *NOT* affect dnotify or
posix locks.
	* permissions are checked as usual along the way to file;
no permission checks are applied to the file itself.  Of course,
giving such thing to syscall will result in permission checks (at
the moment it means checking that starting point of ....at() is
a directory and caller has exec permissions on it).

fget() and fget_light() return NULL on such descriptors; use of
fget_raw() and fget_raw_light() is needed to get them.  That protects
existing code from dealing with those things.

There are two things still missing (they come in the next commits):
one is handling of symlinks (right now we refuse to open them that
way; see the next commit for semantics related to those) and another
is descriptor passing via SCM_RIGHTS datagrams.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

In get_empty_filp() since 2.6.29, file_free(f) is called with f->f_cred == NULL
when security_file_alloc() returned an error.  As a result, kernel will panic()
due to put_cred(NULL) call within RCU callback.

Fix this bug by assigning f->f_cred before calling security_file_alloc().
Signed-off-by: NTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There's an unlikely() in fget_light() that assumes the file ref count
will be 1. Running the annotate branch profiler on a desktop that is
performing daily tasks (running firefox, evolution, xchat and is also part
of a distcc farm), it shows that the ref count is not 1 that often.

 correct incorrect      %    Function                  File              Line
 ------- ---------      -    --------                  ----              ----
1035099358 6209599193  85    fget_light              file_table.c         315

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Robin Holt tried to boot a 16TB system and found af_unix was overflowing
a 32bit value :

<quote>

We were seeing a failure which prevented boot.  The kernel was incapable
of creating either a named pipe or unix domain socket.  This comes down
to a common kernel function called unix_create1() which does:

        atomic_inc(&unix_nr_socks);
        if (atomic_read(&unix_nr_socks) > 2 * get_max_files())
                goto out;

The function get_max_files() is a simple return of files_stat.max_files.
files_stat.max_files is a signed integer and is computed in
fs/file_table.c's files_init().

        n = (mempages * (PAGE_SIZE / 1024)) / 10;
        files_stat.max_files = n;

In our case, mempages (total_ram_pages) is approx 3,758,096,384
(0xe0000000).  That leaves max_files at approximately 1,503,238,553.
This causes 2 * get_max_files() to integer overflow.

</quote>

Fix is to let /proc/sys/fs/file-nr & /proc/sys/fs/file-max use long
integers, and change af_unix to use an atomic_long_t instead of atomic_t.

get_max_files() is changed to return an unsigned long.  get_nr_files() is
changed to return a long.

unix_nr_socks is changed from atomic_t to atomic_long_t, while not
strictly needed to address Robin problem.

Before patch (on a 64bit kernel) :
# echo 2147483648 >/proc/sys/fs/file-max
# cat /proc/sys/fs/file-max
-18446744071562067968

After patch:
# echo 2147483648 >/proc/sys/fs/file-max
# cat /proc/sys/fs/file-max
2147483648
# cat /proc/sys/fs/file-nr
704     0       2147483648
Reported-by: NRobin Holt <holt@sgi.com>
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Acked-by: NDavid Miller <davem@davemloft.net>
Reviewed-by: NRobin Holt <holt@sgi.com>
Tested-by: NRobin Holt <holt@sgi.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Andrew,

Could you please review this patch, you probably are the right guy to
take it, because it crosses fs and net trees.

Note : /proc/sys/fs/file-nr is a read-only file, so this patch doesnt
depend on previous patch (sysctl: fix min/max handling in
__do_proc_doulongvec_minmax())

Thanks !

[PATCH V4] fs: allow for more than 2^31 files

Robin Holt tried to boot a 16TB system and found af_unix was overflowing
a 32bit value :

<quote>

We were seeing a failure which prevented boot.  The kernel was incapable
of creating either a named pipe or unix domain socket.  This comes down
to a common kernel function called unix_create1() which does:

        atomic_inc(&unix_nr_socks);
        if (atomic_read(&unix_nr_socks) > 2 * get_max_files())
                goto out;

The function get_max_files() is a simple return of files_stat.max_files.
files_stat.max_files is a signed integer and is computed in
fs/file_table.c's files_init().

        n = (mempages * (PAGE_SIZE / 1024)) / 10;
        files_stat.max_files = n;

In our case, mempages (total_ram_pages) is approx 3,758,096,384
(0xe0000000).  That leaves max_files at approximately 1,503,238,553.
This causes 2 * get_max_files() to integer overflow.

</quote>

Fix is to let /proc/sys/fs/file-nr & /proc/sys/fs/file-max use long
integers, and change af_unix to use an atomic_long_t instead of
atomic_t.

get_max_files() is changed to return an unsigned long.
get_nr_files() is changed to return a long.

unix_nr_socks is changed from atomic_t to atomic_long_t, while not
strictly needed to address Robin problem.

Before patch (on a 64bit kernel) :
# echo 2147483648 >/proc/sys/fs/file-max
# cat /proc/sys/fs/file-max
-18446744071562067968

After patch:
# echo 2147483648 >/proc/sys/fs/file-max
# cat /proc/sys/fs/file-max
2147483648
# cat /proc/sys/fs/file-nr
704     0       2147483648
Reported-by: NRobin Holt <holt@sgi.com>
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Acked-by: NDavid Miller <davem@davemloft.net>
Reviewed-by: NRobin Holt <holt@sgi.com>
Tested-by: NRobin Holt <holt@sgi.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

fs: scale files_lock

Improve scalability of files_lock by adding per-cpu, per-sb files lists,
protected with an lglock. The lglock provides fast access to the per-cpu lists
to add and remove files. It also provides a snapshot of all the per-cpu lists
(although this is very slow).

One difficulty with this approach is that a file can be removed from the list
by another CPU. We must track which per-cpu list the file is on with a new
variale in the file struct (packed into a hole on 64-bit archs). Scalability
could suffer if files are frequently removed from different cpu's list.

However loads with frequent removal of files imply short interval between
adding and removing the files, and the scheduler attempts to avoid moving
processes too far away. Also, even in the case of cross-CPU removal, the
hardware has much more opportunity to parallelise cacheline transfers with N
cachelines than with 1.

A worst-case test of 1 CPU allocating files subsequently being freed by N CPUs
degenerates to contending on a single lock, which is no worse than before. When
more than one CPU are allocating files, even if they are always freed by
different CPUs, there will be more parallelism than the single-lock case.

Testing results:

On a 2 socket, 8 core opteron, I measure the number of times the lock is taken
to remove the file, the number of times it is removed by the same CPU that
added it, and the number of times it is removed by the same node that added it.

Booting:    locks=  25049 cpu-hits=  23174 (92.5%) node-hits=  23945 (95.6%)
kbuild -j16 locks=2281913 cpu-hits=2208126 (96.8%) node-hits=2252674 (98.7%)
dbench 64   locks=4306582 cpu-hits=4287247 (99.6%) node-hits=4299527 (99.8%)

So a file is removed from the same CPU it was added by over 90% of the time.
It remains within the same node 95% of the time.

Tim Chen ran some numbers for a 64 thread Nehalem system performing a compile.

                throughput
2.6.34-rc2      24.5
+patch          24.9

                us      sys     idle    IO wait (in %)
2.6.34-rc2      51.25   28.25   17.25   3.25
+patch          53.75   18.5    19      8.75

So significantly less CPU time spent in kernel code, higher idle time and
slightly higher throughput.

Single threaded performance difference was within the noise of microbenchmarks.
That is not to say penalty does not exist, the code is larger and more memory
accesses required so it will be slightly slower.

Cc: linux-kernel@vger.kernel.org
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Signed-off-by: NNick Piggin <npiggin@kernel.dk>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

fs: cleanup files_lock locking

Lock tty_files with a new spinlock, tty_files_lock; provide helpers to
manipulate the per-sb files list; unexport the files_lock spinlock.

Cc: linux-kernel@vger.kernel.org
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Acked-by: NAndi Kleen <ak@linux.intel.com>
Acked-by: NGreg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: NNick Piggin <npiggin@kernel.dk>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

This reverts commit 3bcf3860 (and the
accompanying commit c1e5c954 "vfs/fsnotify: fsnotify_close can delay
the final work in fput" that was a horribly ugly hack to make it work at
all).

The 'struct file' approach not only causes that disgusting hack, it
somehow breaks pulseaudio, probably due to some other subtlety with
f_count handling.

Fix up various conflicts due to later fsnotify work.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Improve the description of fget_light(), which is currently incorrect
about needing a prior refcnt (judging by the way it is actually used).
Signed-off-by: NTony Battersby <tonyb@cybernetics.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

fanotify almost works like so:

user context calls fsnotify_* function with a struct file.
   fsnotify takes a reference on the struct path
user context goes about it's buissiness

at some later point in time the fsnotify listener gets the struct path
   fanotify listener calls dentry_open() to create a file which userspace can deal with
      listener drops the reference on the struct path
at some later point the listener calls close() on it's new file

With the switch from struct path to struct file this presents a problem for
fput() and fsnotify_close().  fsnotify_close() is called when the filp has
already reached 0 and __fput() wants to do it's cleanup.

The solution presented here is a bit odd.  If an event is created from a
struct file we take a reference on the file.  We check however if the f_count
was already 0 and if so we take an EXTRA reference EVEN THOUGH IT WAS ZERO.
In __fput() (where we know the f_count hit 0 once) we check if the f_count is
non-zero and if so we drop that 'extra' ref and return without destroying the
file.
Signed-off-by: NEric Paris <eparis@redhat.com>

__aio_put_req() plays sick games with file refcount.  What
it wants is fput() from atomic context; it's almost always
done with f_count > 1, so they only have to deal with delayed
work in rare cases when their reference happens to be the
last one.  Current code decrements f_count and if it hasn't
hit 0, everything is fine.  Otherwise it keeps a pointer
to struct file (with zero f_count!) around and has delayed
work do __fput() on it.

Better way to do it: use atomic_long_add_unless( , -1, 1)
instead of !atomic_long_dec_and_test().  IOW, decrement it
only if it's not the last reference, leave refcount alone
if it was.  And use normal fput() in delayed work.

I've made that atomic_long_add_unless call a new helper -
fput_atomic().  Drops a reference to file if it's safe to
do in atomic (i.e. if that's not the last one), tells if
it had been able to do that.  aio.c converted to it, __fput()
use is gone.  req->ki_file *always* contributes to refcount
now.  And __fput() became static.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

We'll introduce FMODE_RANDOM which will be runtime modified.  So protect
all runtime modification to f_mode with f_lock to avoid races.
Signed-off-by: NWu Fengguang <fengguang.wu@intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: <stable@kernel.org>			[2.6.33.x]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Hooks: Just Say No.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

When alloc_file() and init_file() were combined, the error handling of
mnt_clone_write() was taken into alloc_file() in a somewhat obfuscated
way.  Since we don't use the error code for anything except warning,
we might as well warn directly without an extra variable.
Signed-off-by: NRoland Dreier <rolandd@cisco.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Commit 3d1e4631 ("get rid of init_file()") removed the export of
alloc_file() -- possibly inadvertently, since that commit mainly
consisted of deleting the lines between the end of alloc_file() and
the start of the code in init_file().

There is in fact one modular use of alloc_file() in the tree, in
drivers/infiniband/core/uverbs_main.c, so re-add the export to fix:

    ERROR: "alloc_file" [drivers/infiniband/core/ib_uverbs.ko] undefined!

when CONFIG_INFINIBAND_USER_ACCESS=m.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NRoland Dreier <rolandd@cisco.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There are 2 groups of alloc_file() callers:
	* ones that are followed by ima_counts_get
	* ones giving non-regular files
So let's pull that ima_counts_get() into alloc_file();
it's a no-op in case of non-regular files.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

All users outside of fs/ of get_empty_filp() have been removed.  This patch
moves the definition from the include/ directory to internal.h so no new
users crop up and removes the EXPORT_SYMBOL.  I'd love to see open intents
stop using it too, but that's a problem for another day and a smarter
developer!
Signed-off-by: NEric Paris <eparis@redhat.com>
Acked-by: NMiklos Szeredi <miklos@szeredi.hu>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

... and have the caller grab both mnt and dentry; kill
leak in infiniband, while we are at it.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Based on discussions on LKML and LSM, where there are consecutive
security_ and ima_ calls in the vfs layer, move the ima_ calls to
the existing security_ hooks.
Signed-off-by: NMimi Zohar <zohar@us.ibm.com>
Signed-off-by: NJames Morris <jmorris@namei.org>

It's unused.

It isn't needed -- read or write flag is already passed and sysctl
shouldn't care about the rest.

It _was_ used in two places at arch/frv for some reason.
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Cc: David Howells <dhowells@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This function walks the s_files lock, and operates primarily on the
files in a superblock, so it better belongs here (eg. see also
fs_may_remount_ro).

[AV: ... and it shouldn't be static after that move]
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

This patch speeds up lmbench lat_mmap test by about another 2% after the
first patch.

Before:
 avg = 462.286
 std = 5.46106

After:
 avg = 453.12
 std = 9.58257

(50 runs of each, stddev gives a reasonable confidence)

It does this by introducing mnt_clone_write, which avoids some heavyweight
operations of mnt_want_write if called on a vfsmount which we know already
has a write count; and mnt_want_write_file, which can call mnt_clone_write
if the file is open for write.

After these two patches, mnt_want_write and mnt_drop_write go from 7% on
the profile down to 1.3% (including mnt_clone_write).

[AV: mnt_want_write_file() should take file alone and derive mnt from it;
not only all callers have that form, but that's the only mnt about which
we know that it's already held for write if file is opened for write]

Cc: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

'struct path' is not used in alloc_file().
Signed-off-by: NTero Roponen <tero.roponen@gmail.com>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

This lock moves out of the CONFIG_EPOLL ifdef and becomes f_lock.  For now,
epoll remains the only user, but a future patch will use it to protect
f_flags as well.

Cc: Davide Libenzi <davidel@xmailserver.org>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>

This patch replaces the generic integrity hooks, for which IMA registered
itself, with IMA integrity hooks in the appropriate places directly
in the fs directory.
Signed-off-by: NMimi Zohar <zohar@us.ibm.com>
Acked-by: NSerge Hallyn <serue@us.ibm.com>
Signed-off-by: NJames Morris <jmorris@namei.org>

Instead of creating the "filp" kmem_cache in vfs_caches_init(),
we can do it a litle be later in files_init(), so that filp_cachep
is static to fs/file_table.c
Acked-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: NEric Dumazet <dada1@cosmosbay.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Attach creds to file structs and discard f_uid/f_gid.

file_operations::open() methods (such as hppfs_open()) should use file->f_cred
rather than current_cred().  At the moment file->f_cred will be current_cred()
at this point.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Reviewed-by: NJames Morris <jmorris@namei.org>
Signed-off-by: NJames Morris <jmorris@namei.org>

Wrap current->cred and a few other accessors to hide their actual
implementation.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Acked-by: NJames Morris <jmorris@namei.org>
Acked-by: NSerge Hallyn <serue@us.ibm.com>
Signed-off-by: NJames Morris <jmorris@namei.org>

Separate the task security context from task_struct.  At this point, the
security data is temporarily embedded in the task_struct with two pointers
pointing to it.

Note that the Alpha arch is altered as it refers to (E)UID and (E)GID in
entry.S via asm-offsets.

With comment fixes Signed-off-by: Marc Dionne <marc.c.dionne@gmail.com>
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Acked-by: NJames Morris <jmorris@namei.org>
Acked-by: NSerge Hallyn <serue@us.ibm.com>
Signed-off-by: NJames Morris <jmorris@namei.org>

As it is, all instances of ->release() for files that have ->fasync()
need to remember to evict file from fasync lists; forgetting that
creates a hole and we actually have a bunch that *does* forget.

So let's keep our lives simple - let __fput() check FASYNC in
file->f_flags and call ->fasync() there if it's been set.  And lose that
crap in ->release() instances - leaving it there is still valid, but we
don't have to bother anymore.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

make it atomic_long_t; while we are at it, get rid of useless checks in affs,
hfs and hpfs - ->open() always has it equal to 1, ->release() - to 0.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Initial splitoff of the low-level stuff; taken to fdtable.h
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

There have been a few oopses caused by 'struct file's with NULL f_vfsmnts.
There was also a set of potentially missed mnt_want_write()s from
dentry_open() calls.

This patch provides a very simple debugging framework to catch these kinds of
bugs.  It will WARN_ON() them, but should stop us from having any oopses or
mnt_writer count imbalances.

I'm quite convinced that this is a good thing because it found bugs in the
stuff I was working on as soon as I wrote it.

[hch: made it conditional on a debug option.
      But it's still a little bit too ugly]

[hch: merged forced remount r/o fix from Dave and akpm's fix for the fix]
Signed-off-by: NDave Hansen <haveblue@us.ibm.com>
Acked-by: NAl Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

This is the first really tricky patch in the series.  It elevates the writer
count on a mount each time a non-special file is opened for write.

We used to do this in may_open(), but Miklos pointed out that __dentry_open()
is used as well to create filps.  This will cover even those cases, while a
call in may_open() would not have.

There is also an elevated count around the vfs_create() call in open_namei().
See the comments for more details, but we need this to fix a 'create, remount,
fail r/w open()' race.

Some filesystems forego the use of normal vfs calls to create
struct files.   Make sure that these users elevate the mnt
writer count because they will get __fput(), and we need
to make sure they're balanced.
Acked-by: NAl Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDave Hansen <haveblue@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

If someone decides to demote a file from r/w to just
r/o, they can use this same code as __fput().

NFS does just that, and will use this in the next
patch.

AV: drop write access in __fput() only after we evict from file list.
Signed-off-by: NDave Hansen <haveblue@us.ibm.com>
Cc: Erez Zadok <ezk@cs.sunysb.edu>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: "J Bruce Fields" <bfields@fieldses.org>
Acked-by: NAl Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>